Manufacturing method of substrate for a semiconductor package, manufacturing method of semiconductor package, substrate for a semiconductor package and semiconductor package

ABSTRACT

A manufacturing method of a substrate for a semiconductor package includes a resist layer forming step to form a resist layer on a surface of a conductive substrate; an exposure step to expose the resist layer using a glass mask with a mask pattern including a transmission area, a light shielding area, and an intermediate transmission area, wherein transmittance of the intermediate transmission area is lower than that of the transmission area and is higher than that of the light shielding area; a development step to form a resist pattern including a hollow with a side shape including a slope part decreasing in hollow circumference as the hollow circumference approaches the substrate; and a plating step to plate on an exposed area to form a metal layer with a side shape including a slope part decreasing in circumference as the circumference approaches the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based upon and claims the benefit of priorityof Japanese Patent Application No. 2009-38563 filed on Feb. 20, 2009 andJapanese Patent Application No. 2010-000305 filed on Jan. 5, 2010 theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing method of a substratefor a semiconductor package, a manufacturing method semiconductorpackage, a substrate for a semiconductor package and a semiconductorpackage.

2. Description of the Related Art

Conventionally, a semiconductor package manufacturing method where asemiconductor device is sealed with resin is known as disclosed inJapanese Published Patent Application No. 2002-9196 (which ishereinafter called “Patent Document 1”). In the semiconductormanufacturing method, to begin with, a resist pattern layer with apredetermined pattern is formed on a conductive surface of a substrate.Then, conductive metal is electrodeposited on an exposed surface of theconductive surface of the substrate uncovered with the resist patternlayer so that a thickness of the conductive metal is over that of theresist pattern layer, by which a metal layer for semiconductor devicemounting and electrode layers are respectively formed so as to haveflared portions. After removing the resist pattern layer, asemiconductor device is mounted on the metal layer, and electrodes onthe semiconductor device are electronically connected to the electrodelayers by bonding wires. Finally, the semiconductor device mounting partis sealed with resin, and the substrate is removed. As a result, backsurfaces of the metal layer and electrode layers are exposed, and asemiconductor device in a resin sealed body, a semiconductor package, isobtained.

According to the semiconductor package manufacturing method, because theflared portions are set to bite into the resin, binding power isimproved due to the effect of biting. This helps important parts such asthe metal layer and electrode layers stay in the resin sealed bodywithout being pulled apart by sticking to the substrate, which caneffectively prevent displacement and lack of the important parts. Thesemiconductor package manufacturing method also serves to ensure bondingstrength after soldering the semiconductor device on a substrate forelectronic components.

In addition, the characteristic flared shape formed around a wholecircumference of a top edge of the metal layer and the electrode layerscan prevent water from intruding from a backside of the semiconductorpackage through a boundary division between the metal layer or each ofthe electrode layers and the sealing resin layer, which can improvehumidity resistance of the semiconductor package.

However, according to a configuration of Patent Document 1, because theelectrodeposition is made over the resist pattern and not controlled bythe resist pattern in a transverse direction, the electrodepositionprocess is susceptible to the effect of a distribution of currentdensity, which makes it difficult to keep the length of the flaredportions constant. This causes variation in the binding power betweenthe electrode layers or metal layer and the resin. In addition, becausethe electrodeposition process is performed without any control by theresist pattern of its top surface, the top surface does not become flat,and a poor connection of a bonding wire tends to occur.

In recent years, because of semiconductor package downsizing advances,and semiconductor devices used for the semiconductor package have alsotended to be miniaturized, an electrode layer of a substrate for asemiconductor device needs to be miniaturized and to realize highaccuracy.

However, as disclosed in Patent Document 1, if the size of an electrodelayer provided corresponding to a semiconductor device cannot becontrolled with a high degree of accuracy, there is a concern thatadapting miniaturization in the future may be impossible. Moreover, toobtain a certain biting effect between the electrode layers or metallayer and the resin, a length of the flared portion needs to be in arange of 5 to 20 μm. However, because a necessary thickness of theelectrode layers and metal layer increases as the flared portion becomeslonger, there is a concern that the semiconductor package manufacturingmethod disclosed in Patent Document 1 cannot be adapted to a tendencyfor a thinner semiconductor package.

SUMMARY OF THE INVENTION

Accordingly, embodiments of the present invention may provide a noveland useful manufacturing method of a substrate for a semiconductorpackage, a manufacturing method of a semiconductor package, a substratefor a semiconductor package and a semiconductor package solving one ormore of the problems discussed above.

More specifically, the embodiments of the present invention may providea manufacturing method of a substrate for a semiconductor package, amanufacturing method of a semiconductor package, a substrate for asemiconductor package, and a semiconductor package whereby a size of ametal layer and an electrode layer is uniform; binding power of sealingresin is stable and strong; an electrode top surface is flat enough tohave a superior bonding ability; and adaptation to miniaturization andreducing a thickness of a semiconductor package is possible.

One aspect of the present invention may be to provide a manufacturingmethod of a substrate for a semiconductor package including,

a resist layer forming step to form a resist layer on a surface of aconductive substrate;

a lithographic exposure step to expose the resist layer using a glassmask with a mask pattern including a transmission area, a lightshielding area, and an intermediate transmission area disposed betweenthe transmission area and the light shielding area, whereintransmittance of the intermediate transmission area is lower than thatof the transmission area and is higher than that of the light shieldingarea;

a development step to develop the resist layer and to form a resistpattern including a hollow with a side shape including a slope partdecreasing in hollow circumference as the hollow circumferenceapproaches to the substrate;

a plating step to plate on an exposed area of the substrate by using theresist pattern and to form a metal layer with a side shape including aslope part decreasing in circumference as the circumference approachesthe substrate; and

a resist removal step to remove the resist pattern.

Another aspect of the present invention may be to provide amanufacturing method of a semiconductor package including,

a resist layer forming step to form a resist layer on a surface of aconductive substrate;

a lithographic exposure step to expose the resist layer using a glassmask with a mask pattern including a transmission area, a lightshielding area, and an intermediate transmission area disposed betweenthe transmission area and the light shielding area, whereintransmittance of the intermediate transmission area is lower than thatof the transmission area and is higher than that of the light shieldingarea;

a development step to develop the resist layer and to form a resistpattern including a hollow with a side shape including a slope partdecreasing in hollow circumference as the hollow circumferenceapproaches the substrate;

a plating step to plate on an exposed area of the substrate by using theresist pattern and to form metal layers with a side shape including aslope part decreasing in circumference as the circumference approachesthe substrate;

a resist removal step to remove the resist pattern;

a semiconductor device mounting step to mount a semiconductor device onone of the metal layers of the substrate;

a wire bonding step to connect a terminal of the semiconductor device toanother metal layer of the metal layers as an electrode;

a sealing step to seal the semiconductor device mounted on one of themetal layers of the substrate with resin; and

a substrate removal step to remove the substrate from the semiconductordevice.

Another aspect of the present invention may be to provide a substratefor a semiconductor package including,

an electrode of a metal layer on a substrate; and

a semiconductor mounting area of a metal layer on the substrate,

wherein at least one of the electrode and the semiconductor mountingarea has a top surface in a zigzag shape and a side surface including aslope part decreasing in circumference and having the zigzag shapedecreasing in size as the circumference approaches the substrate.

Another aspect of the present invention may be to provide asemiconductor package including,

an electrode metal layer including a top surface used for wire bondingand a bottom surface used for an outer terminal;

a semiconductor device mounting metal layer to support a semiconductordevice;

a semiconductor device mounted on the semiconductor device mountingmetal layer and including a terminal connected to the electrode metallayer by the wire bonding; and

a resin body to seal the semiconductor device without sealing the bottomsurface of the electrode metal layer,

wherein at least one of the electrode metal layer and the semiconductordevice mounting metal layer has a top surface in a zigzag shape and aside surface including a slope part decreasing in circumference andhaving the zigzag shape decreasing in size as the circumferenceapproaches a bottom surface.

Additional objects and advantages of the embodiments are set forth inpart in the description which follows, and in part will become obviousfrom the description, or may be learned by practice of the invention.The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe appended claims. It is to be understood that both the foregoinggeneral description and the following detailed description are exemplaryand explanatory and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a semiconductor package of a first embodimentof the present invention;

FIG. 1B is a bottom view of a semiconductor package of a firstembodiment of the present invention;

FIG. 2A is a side view showing an example of a shape of a metal layer;

FIG. 2B is a view showing a plating process of a manufacturing processof a metal layer;

FIG. 3A is a first view of a manufacturing method of a substrate for thesemiconductor package of the first embodiment showing a substrate;

FIG. 3B is a second view of a manufacturing method of a substrate forthe semiconductor package of the first embodiment showing a resistforming process;

FIG. 3C is a third view of a manufacturing method of a substrate for thesemiconductor package of the first embodiment showing a lithographicexposure process;

FIG. 3D is a fourth view of a manufacturing method of a substrate forthe semiconductor package of the first embodiment showing a developingprocess;

FIG. 3E is a fifth view of a manufacturing method of a substrate for thesemiconductor package of the first embodiment showing a resist patternstabilization process;

FIG. 3F is a sixth view of a manufacturing method of a substrate for thesemiconductor package of the first embodiment showing a plating process;

FIG. 3G is a seventh view of a manufacturing method of a substrate forthe semiconductor package of the first embodiment showing a resistremoval process;

FIG. 4 is an explanation view to explain an example of a relationshipbetween a glass mask and a resist pattern;

FIG. 5A is a top view showing an example of a mask pattern in alithographic exposure process in the first embodiment;

FIG. 5B is a view showing an example of a resist pattern formed by usingthe mask pattern of FIG. 5A;

FIG. 6A is a view showing an example of top surface of a metal layerformed by using a resist pattern;

FIG. 6B is a view showing an example of side surface of a metal layerformed by using a resist pattern;

FIG. 6C is a view showing an example of a bottom surface of a metallayer formed by using a resist pattern;

FIG. 6D is a perspective view showing an example of a cubic figure of avertically inverted metal layer;

FIG. 7 is a view showing an example of a mask pattern in themanufacturing method of a substrate for a semiconductor package of thefirst embodiment;

FIG. 8 is a view showing a first modified example of a mask pattern inthe manufacturing method of a substrate for a semiconductor package ofthe first embodiment;

FIG. 9 is a view showing a second modified example of a mask pattern inthe manufacturing method of a substrate for a semiconductor package ofthe first embodiment;

FIG. 10 is a view showing a third modified example of a mask pattern inthe manufacturing method of a substrate for a semiconductor package ofthe first embodiment;

FIG. 11A is a first view of a manufacturing method of a semiconductorpackage of the first embodiment showing a semiconductor device mountingprocess;

FIG. 11B is a second view of a manufacturing method of a semiconductorpackage of the first embodiment showing a wire bonding process;

FIG. 11C is a third view of a manufacturing method of a semiconductorpackage of the first embodiment showing a resin sealing process;

FIG. 11D is a fourth view of a manufacturing method of a semiconductorpackage of the first embodiment showing a substrate removal process;

FIG. 11E is a fifth view of a manufacturing method of a semiconductorpackage of the first embodiment showing a dividing process;

FIG. 12A is an enlarged view showing a metal layer of a substrate for asemiconductor package of a second embodiment of the present invention;

FIG. 12B is a view showing plating process to form the metal layer ofthe substrate for a semiconductor package of the second embodiment ofthe present invention;

FIG. 13A is a view showing an example of a configuration of a maskpattern of the manufacturing method of the substrate for a semiconductorpackage of the second embodiment of the present invention;

FIG. 13B is a view showing an example of a resist pattern of themanufacturing method of the substrate for a semiconductor package of thesecond embodiment of the present invention;

FIG. 14A is a top view showing a metal layer of the substrate for asemiconductor package of the second embodiment;

FIG. 14B is a side view showing the metal layer of the substrate for asemiconductor package of the second embodiment;

FIG. 14C is a bottom view showing the metal layer of the substrate for asemiconductor package of the second embodiment; and

FIG. 14D is a cubic and oblique perspective view showing a verticallyinverted metal layer of the substrate for a semiconductor package of thesecond embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description is given below, with reference to drawings of embodimentsof the present invention.

First Embodiment

FIG. 1A and FIG. 1B are views showing an example of a finished productof a semiconductor package 100 of a first embodiment of the presentinvention. FIG. 1A is a side view showing an example of the finishedproduct of the semiconductor package 100. FIG. 1B is a bottom viewshowing the finished product of the semiconductor package 100.

In FIG. 1A, the semiconductor package 100 of the first embodimentincludes metal layers 40, a semiconductor device 60, bonding wires 70and sealing resin 80.

The metal layers 40 are formed of metal material. The metal layers 40have a top surface 41, a bottom surface 42 and a side surface 43. Forexample, the metal layers 40 may by formed by plating and so on.

The metal layers 40 include a semiconductor device mounting area 45 andan electrode 46. The semiconductor device mounting area 45 is an area tosupport the semiconductor device 60. A surface of the semiconductordevice 60 without a terminal 61 (refer to FIG. 1B) is bonded on the topsurface 41 of the semiconductor device mounting area 45, by which thesemiconductor device 60 is mounted on the semiconductor device mountingarea 45. An end of the bonding wire 70 is connected to the terminal 61of the semiconductor device 60. The electrode 46 is a metal layer thatis electrically connected to the terminal 61 of the semiconductor device60. The other end of the bonding wire 70 is connected to the top surface41 of the electrode 46. The bottom surface 42 of the electrode 46 isexposed and becomes an outer terminal 47 to be able to connect tooutside wiring.

The metal layer 40 has a side surface shape where the width is thegreatest at the top surface 41 and decreases as a level approaches thebottom surface 42, including a tapering slope part 44 such carvedinward. By having a side surface shape including the slope part 44, thewidth of which decreases as the level approaches the bottom surface 42,the sealing resin 80 wraps around the metal layer 40 from a lower side.This prevents a phenomenon where the metal material 40 is pulled outdownward from the sealing resin 80, and can improve humidity resistance.Details on these points are described below.

The semiconductor device 60 is a packaged device as an IC (IntegratedCircuit) that includes a predetermined electronic circuit on asemiconductor chip. The semiconductor device 60 includes pluralterminals 61 for input and output connections to the internal electroniccircuit. However, since the distance between the terminals 61 isextremely short, as shown in FIG. 1A and FIG. 1B, by electricallyconnecting the terminals 61 of the semiconductor device 60 to theelectrodes 46 of the semiconductor package 100 with the bonding wires70, and by using the bottom surfaces 42 of the electrodes 46 as theouter connection terminals 47, connection to an external circuit becomeseasier. Here the bonding wire 70 is a connecting wire between thesemiconductor device 60 and the electrode 46, and various kinds ofmetals for wiring are available for the bonding wire 70.

The sealing resin 80 may be used to fix the semiconductor device 60 andthe bonding wire 70, and to prevent intrusion of dust and water inward.Because the sealing resin 80 can fill up all spaces, the sealing resin80 can also fill up a space around the tapering slope part 44 thatbecomes thinner at a lower part of the metal layer 40. When the sealingresin 80 hardens, the side surface 43 of the metal layer 40 is caught upby the sealing resin 80, which prevents the metal layer 40 from beingpulled out downward from the sealing resin 80. Moreover, due to thetapered shape that becomes gradually thinner toward the bottom surface42 of the metal layer 40, a border length between the metal layer 40 andthe sealing resin 80 is longer than that in a case where the metal layer40 has a vertical side surface 43, which can prevent the water intrusionand improve the humidity resistance.

FIG. 1B shows a bottom view of the semiconductor package 100 of thefirst embodiment. In the bottom surface of the semiconductor package100, the outer terminal 47, which is the bottom surface 42 of theelectrode 46, is exposed and a bottom surface of the semiconductordevice mounting area 45 is also exposed.

Furthermore, FIG. 1B shows that the terminal 61 of the semiconductordevice 60 and the top surface 41 of the electrode 46 are connected bythe bonding wire 70. In this manner, the semiconductor package 100 makesit easier to handle the semiconductor device 60 by connecting the smallterminal 61 of the semiconductor device 60 to the electrode 46 insidethe semiconductor package 100 and by exposing the larger outer terminal47 outside.

In FIG. 1A, a cross-sectional view of FIG. 1B along the line A-A isshown. As well as FIG. 1A, a cross-sectional view of FIG. 1B along theline B-B or C-C may also show the side surface 43 of the electrode 46and the semiconductor device mounting area 45 as a shape of the bottomsurface 42 which is shorter than the top surface 41 in width, includingthe tapered slope part 44. In other words, the semiconductor devicemounting area 45 and electrode 46 may have side shapes including theslope part 44 not only in a traverse direction, but also in alongitudinal direction shown in FIG. 18. In the following explanationsof the embodiment, the explanations are given by citing an example of aside surface of transverse width, but the explanations are applicable toa side surface viewed from a longitudinal direction side in a similarway. Furthermore, since a decrease of a length as well as a decrease ofwidth causes a decrease of circumference, one of the width and length orboth of the width and length can be expressed by using a circumference.The expression of the “width” or “length” can be replaced by the“circumference”.

FIG. 2A and FIG. 2B are side views showing an example of a partialconfiguration of a substrate for a semiconductor package 50 of the firstembodiment of the present invention.

FIG. 2A is a side view showing an example of a shape of the metal layer40 described in the semiconductor package 100 in FIG. 1A and FIG. 1B. InFIG. 2A, the metal layer 40 has a bottom surface 42 the width of whichis narrower than that of a top surface 41, and a side surface 43including a slope part 44 that has a tapering shape carved inward nearthe bottom surface 42 lower than the middle level. By making the metallayer 40 into such a shape, when the sealing resin 80 described in FIG.1A is supplied, the sealing resin 80 holds the side surface 43 of themetal layer 40 not only from a lateral direction but also from a lowerpart upward through the slope part 44. Therefore, the metal layer 40 hasa shape to be able to prevent the metal layer 40 from being pulled outdownward even if a downward force is applied from below. In addition,since the lower part of the metal layer 40 becomes gradually thinner, aborder line between the metal layer 40 and the sealing resin 80 becomeslonger compared to the vertically shaped metal layer of the conventionalart, which can prevent intrusion of water and can improve humidityresistance.

FIG. 2B is a view showing an example of a plating process, one ofprocesses of a manufacturing method of a substrate for a semiconductorpackage including the metal layer 40. In FIG. 2B, the metal layer 40shown in FIG. 2A is formed on a conductive substrate 10, surrounded by aresist pattern 22.

In this way, the semiconductor package 100 shown in FIG. 1A and FIG. 1Bis manufactured by using a substrate for a semiconductor device 50 atfirst. Then, in the end, a bottom surface 42 of the metal layer 40 isexposed by removing the substrate 10. A removing method of the substrate10 may be a method of dissolving the substrate 10 with a solvent thatdoes not affect the sealing resin 80 other than the method of forciblypulling the substrate 10 apart from the sealing resin 80. If thesubstrate 10 is removed by tearing, a downward force pulling the metallayer 40 attached to the substrate 10 acts in a tearing removal step.However, by making the metal layer 40 into a shape including the slopepart 44 that is decreased in width and circumference toward the bottomas shown in FIG. 2B, the sealing resin 80 exists in a part between theslope part 44 and the substrate 10, surrounding an electrodeposiion areaof the metal layer 40 on the substrate 10. This can fix the metal layer40 so as to hold the metal layer 40 from below.

The metal layer 40 having such a shape, for example, can be formed byusing a resist pattern 22 as shown in FIG. 2B. More specifically, FIG.2B shows a resist pattern 22 surrounding the metal layer 40. As shown inFIG. 2B, the resist pattern 22 is formed to have a hollow of whichopening size decreases inward and downward. Then, by plating to fill thehollow formed on the exposed substrate 10 with the resist pattern 22,the metal layer 40 with a side surface including the slope part 44carved inward can be formed. As shown in FIG. 2B, the side shape of themetal layer 40 can be completely controlled by the resist pattern 22.Furthermore, by plating in a thickness less than that of the resistpattern 22, a top surface 41 of the metal layer 40 can be formed evenly.In addition, because plating is not performed at a level over the resistpattern 22, the metal layer 40 can be formed thin, which can contributeto making the semiconductor package 100 thinner.

Thus, the substrate for a semiconductor package 50 of the firstembodiment is manufactured by forming a metal layer 40 of which shape iscontrolled by using a resist pattern 22. Hereinafter, a concretemanufacturing method of the substrate for a semiconductor package 50 ofthe first embodiment is more specifically described.

FIG. 3A through FIG. 3G are views showing an example of a manufacturingmethod of a substrate for a semiconductor package 50 of the firstembodiment of the present invention.

FIG. 3A is a view showing a substrate 10. The substrate 10 can be madeof a variety of materials including metal as long as the materials havea conductive property. The substrate 10, for example, may be made ofstainless or copper metals. Also, regarding the thickness of thesubstrate 10, a variety of thicknesses of the substrate 10 are availableaccording to application. For example, a stainless-steel substrate 0.18mm thick is available.

FIG. 3B is a view showing a resist forming process to form resist layers21 on both sides of the substrate 10. A variety of resists are availablefor the resist layer 21. For example, photo sensitive dry resist isavailable for the resist layer 21. Moreover, the thickness of the resistlayer 21 can be arbitrarily set according to application. For example,the resist layer 21 on a top surface side of the substrate 10 may beabout 75 μm thick, and the resist layer 21 on a bottom surface side ofthe substrate 10 may be about 25 μm thick. Furthermore, for example,photo resist used for lithographic exposure by light or electrons isavailable for the resist.

FIG. 3C is a view showing a lithography exposure process to expose theresist layer 21. In the lithography exposure process, the resist layer21 is covered with a glass mask 30 where a predetermined mask pattern isformed and irradiated with light; and then, the mask pattern istransferred into the resist layer 21. A negative type resist thatdecreases its solubility and hardens when exposed, and leaves an exposedpart in developer, may be available for the resist. Also, a positivetype resist that increases its solubility when exposed, an exposed partof which dissolves in developer, may be available for the resist. InFIG. 3C through FIG. 3G, an example using the negative type resist isexplained.

In FIG. 3C, because a resist pattern is formed into the resist layer 21on the top surface side, and a resist pattern is not formed into theresist layer 21 on the bottom surface side, the top surface is exposedwith a glass mask 30, and the bottom surface is directly exposed withouta glass mask 30. If a positive type resist is used, exposure should beperformed from the top side with a glass mask 30 having a reversepattern to the negative type resist, without exposure from the bottomsurface.

The glass mask 30 includes a predetermined mask pattern 31. For example,the mask pattern 31 is formed into the glass mask 30 by forming a lightshielding part 38 made of a light shielding film on a glass substrate37. The mask pattern 31 is formed as a pattern including a glasssubstrate exposed part for an area where the resist layer 21 is left andthe light shielding part 38 for an area where the resist layer 21 is notleft. A concrete configuration of the mask pattern 31 of the glass mask10 used in FIG. 3C is described below.

Here an exposure energy amount for the top surface is desired to be70-85% of a rated exposure energy amount for the negative resist. Asmentioned above, details of the mask pattern 31 of the glass mask 30 aredescribed below, but in the embodiment, in order to form a resistpattern 22 with a side shape described in FIG. 2B, the mask pattern 31needs a specific configuration in a border area between the shieldingpart 38 of the glass mask 30 and the glass substrate 37 exposed part.The mask pattern 31 in the border area including the specificconfiguration is provided to adjust transmittance of the border area,but there is a concern that the specific configuration be transferred tothe resist layer 21 without modification if the exposure is performed inthe rated exposure energy amount. Hence, it is desirable to perform theexposure at a lesser exposure energy amount than the rated exposureenergy amount, in order to make the border area between the lightshielding part 38 and the glass substrate 37 in the glass mask 30 havean intermediate transmittance between the light shielding part 3B andthe glass substrate 37, and to form a desired resist pattern 22.

FIG. 3D is a view showing a development process to form the resistpattern 22 into the resist layer 21. In the development process, thesubstrate 10 covered with the resist layer 21 after the exposure isimmersed in developer, an unnecessary part of the resist layer 21 isremoved, and the resist pattern 22 is formed. Various kinds ofdevelopers can be used according to application. For example, sodiumcarbonate solution may be used as the developer.

During the development, it is possible to immerse the substrate 10 inthe developer facing the resist pattern formation surface downward, tothrow a jet of the developer from below toward the resist patternformation surface with a nozzle or the like, and to hit the resistpattern formation surface with the jet of the developer. By providingthe developer to the resist pattern formation surface in this manner, itis possible to prevent stagnation of the developer on the resist patternformation surface and to prevent a poor resist pattern formation byover-development. Also, in this case, since a non-resist pattern formedsurface lies at a top surface, removal of the resist layer 21 by thedevelopment is not carried out about the top surface. Moreover, becausethe non-resist pattern formed surface is flat, it is possible to readilyremove the developer from the non-resist pattern formed surface and toquickly dry the non-resist pattern formed surface after the development.

Regarding a general developing time, when a material surface is observedby eye, if a time when a resist residue is completely removed is made aminimum developing time t0 seconds, and an actual developing time ismade t1 seconds, a developing time coefficient K is expressed asK=t1/t0. In general, the actual developing time t1 seconds is determinedso that the developing time coefficient K equals 1.5 to 2.0 if thesubstrate 10 is made of copper (Cu), and the developing time coefficientK equals 1.2 to 1.6 if the substrate 10 is made of stainless. Thedeveloping time coefficient K of copper is more than 1.5, which is arelatively high value. This is because a safety margin is taken intoaccount to completely remove an unnecessary part of the resist layer 21,considering variation of developing devices and developing conditions.Moreover, the developing time coefficient K of stainless is less thanthat of copper because resist adhesion of stainless is inferior to thatof copper.

However, in the manufacturing method of the substrate for asemiconductor package 50 of the embodiment, it is desirable to determinethe actual developing time t1 seconds so that the developing timecoefficient K is in a range of 1.10 to 1.30 if the substrate 10 is madeof copper; and the developing time coefficient K is in a range of 1.03to 1.09 if the substrate 10 is made of stainless because the resistpattern formation defect rate increases if the developing time is toolong or too short. This is because, as mentioned above, since the borderarea between the shielding part 38 of the glass mask 30 and the exposedpart of the glass substrate 37 needs an intermediate transmittancebetween the shielding part 38 and the exposed part of the glasssubstrate 37, the exposure is performed under the conditions, and thecuring degree of the resist layer 21 in the border area also becomes anintermediate value between the shielding part 38 and the exposed part ofthe glass substrate 37. In other words, according to the generaldeveloping time coefficient K described above, the border area becomesover-developed, and the resist pattern formation defect rate increases.Thus, in the manufacturing method of the substrate for a semiconductorpackage 50 of the embodiment, it is desirable to set the developing timecoefficient K to be more than 1.00, and to be less than the lower limitof a range of the developing time coefficient K in a general developmentprocess.

By the development process, the resist pattern 22 is formed on the topsurface of the substrate 10, and the top surface of the substrate 10includes a part of the remaining resist pattern 22 and an exposed partof the substrate 10. The bottom surface of the substrate 10 is stillcovered with resist layer 21.

The formed resist pattern 22 becomes a shape of which side surface 24includes a slope part 25 that extends downward and outward. Morespecifically, the top surface 23 of the resist pattern 22 and the bottomsurface in contact with the substrate 10 differ in shape, and the resistpattern 22 has a shape the bottom surface of which expands in atransverse direction. The slope part 25 has a shape decreasing in hollowcircumference as the hollow circumference approaches the bottom surface,e.g. the substrate 10. The shape agrees with the shape of the resistpattern 22 described in FIG. 2B. Therefore, in the development processof the manufacturing method of the substrate for a semiconductor package50 of the first embodiment, the resist pattern 22, like a mountain,including a side surface 24 that flares out at the bottom is formed.

FIG. 3E is a view showing a resist pattern stabilization process. Theresist pattern stabilization process is a process provided as necessary,in order to stabilize the resist pattern 22 after the resist pattern 22formation. In the resist pattern stabilization process, after the resistpattern 22 is formed, the surface on which the resist pattern 22 isformed is exposed again, and the side surface 24 of the intermediatecuring degree is fully hardened. This stabilizes the shape of the sidesurface 24 of the resist pattern 22 including the slope part 25, whichmakes it possible to perform the following processes by using a resistpattern 22 of which shape is fixed. Regarding a surface on which theresist pattern 22 is not formed, since a resist layer 21 has alreadyfully hardened, the exposure is not needed.

Moreover, an exposure energy amount in the resist pattern stabilizationprocess is desired to be in a range of 80 mJ/cm² to 120 mJ/cm². Thismakes it possible to fully harden the resist layer 21 exposed in theborder area between the shielding part 38 of the mask pattern 31 and theexposed part of the glass substrate 37, and to certainly stabilize theshape of the side surface 24 of the resist pattern 22.

The resist pattern stabilization process can be called anafter-development lithography exposure process because the resistpattern stabilization process is a lithography exposure processperformed after the development. Furthermore, the resist patternstabilization process can be carried out as necessary, according to aresist pattern condition after the development, process cost, andrequired specifications.

According to the resist pattern stabilization process of the embodiment,even if the side surface of the resist pattern 22 has an insufficientcuring degree after exposed by the intermediate transmission area of themask pattern 31, it is possible to harden the resist pattern 22 enough,and then to perform a plating process after stabilizing the resistpattern 22.

FIG. 3F is a view showing a plating process. In the plating process, anexposed part of the conductive substrate 10 is filled with metalmaterial according to the shape of the resist pattern 22, and the metallayer 40 is formed. The plating may be performed by immersing thesubstrate 10 on which the resist pattern is formed in plating solution,then connecting the substrate 10 to a cathode and placing an anode toface the substrate 10, and performing electroplating. The metal materialused for the plating, for example, may be made of not only one such asgold, but may include plural kinds of materials. In this case, forexample, by performing plural plating operations with different platingsolutions, plating by stacking plural kinds of metal materials can becarried out. For example, from the substrate 10 side, by plating gold(Au) in 0.1 mm film thickness at first, next by plating nickel (Ni) in50 μm film thickness, and finally by plating gold again in 0.3 μmthickness, the plating process can be executed. This makes it possibleto utilize advantages of each of the metal materials and to performhigh-quality plating.

In the plating, since the metal material is electrically deposited on aexposed part of the substrate 10 according to the shape of the resistpattern 22, the metal layer 40 including a top surface 41, thecircumference of which is greater than that of a bottom surface, andincluding a cupped side surface shape including a slope part 44 where aside surface 43 expands from the bottom surface 42 to the top surface41, is formed in accordance with the shape of the resist pattern 22. Bydoing this, when a semiconductor package 100 is manufactured by thesubstrate for a semiconductor package 50, because the sealing resin 80wraps an area under the metal layer 40 around, even if a downward forceacts on the metal layer 40 from below, by fixing the sloped side surface43 or by providing an upward force, resisting the downward force frombelow becomes possible.

It is desirable to make the thickness of the plated metal layer 40 lessthan the thickness of the resist pattern 22. This allows the top surface41 of the metal layer 40 to be formed as a flat surface, and the topsurface and the size of each of semiconductor device mounting areas 45and electrodes 46 to be uniform. Due to this, when a semiconductordevice 60 is mounted on the semiconductor device mounting area 45 orwire bonding is performed on the electrode 46, it is possible to makecertain the adhesion or connection and to decrease product variation ofthe substrates for a semiconductor device 50.

More specifically, if plating is performed over a thickness of theresist pattern 22 like the conventional art disclosed in Patent Document1, the top surface 41 cannot be controlled because the metal overflowsout of the resist pattern 22 and expands transversely on the resistpattern 22. Furthermore, since the length of expanding transverselydiffers among the metal layers 40, the size of the semiconductor devicemounting areas 45 or the electrodes 46 becomes non-uniform. From thisaspect, according to the manufacturing method of the substrate for asemiconductor package 50, the top surface 41 of the semiconductor devicemounting area 45 and electrode 46 can be flat and have a uniform shapeand size. In addition, because the semiconductor device mounting area 45and electrode 46 become lower than the thickness of the resist pattern22, it is possible to shape the semiconductor device mounting area 45and electrode 46 thinner than those in the conventional art.

FIG. 3G is a view showing a resist removal process to remove the resistpattern 22. In the resist removal process, the process can be carriedout by using an appropriate etching solution to remove the used resist,and by immersing the plated substrate 10 in the etching solution. Forexample, if the dry film resist described in FIG. 3B is used as theresist layer 21, 5% caustic soda is available for the etching solution.

In the resist removal process, the resist pattern 22 is removed, and thesubstrate for a semiconductor package 50, which is the conductivesubstrate 10 on which the semiconductor device mounting areas 45 andelectrodes 46 are formed, is completed. Each of the semiconductor devicemounting areas 45 and electrodes 46 have a top surface 41 larger than abottom surface 42 and a side surface 43 including a slope part 44 ofwhich circumference expands from the bottom surface 42 to the topsurface 41. More specifically, if a semiconductor package 100 ismanufactured by using the substrate for a semiconductor package 50, themetal layer 40 has a shape that makes it difficult to be pulled outbecause the metal layer 40 has a slope surface that can resist adownward force by the sealing resin 80 wrapping around an area under themetal layer 40. Moreover, because the semiconductor device mountingareas 45 and electrodes 46 are configured as metal layers 40 that have auniform size and height, each of which has a flat top surface 41, thesubstrate for a semiconductor package 50 is a high-accuracy substratethat can be sufficiently adapted to miniaturization of interconnections.

Next, more detailed explanation is given about the lithography exposureprocess in the manufacturing method of the substrate for a semiconductorpackage 50 of the first embodiment by using FIG. 4 through FIG. 10.

FIG. 4 is a view for explaining an example of a relationship between theglass mask 30 used in the lithography exposure process and the resistpattern 22. In FIG. 4, as the glass mask 30 used for the lithographyexposure, a glass mask 30 including an intermediate transmittance areaof 30% other than a 0% transmittance area and a 100% transmittance areais shown.

The 100% transmittance area is a transmission area where a glasssubstrate 37 is exposed. A resist layer 21 is irradiated with lightemitted by the lithography exposure at 100%. In the 100% transmittancearea, light curing photo resist fully hardens due to the 100%transmitting irradiation light. In contrast, the 0% transmittance areais a shielding area that blocks off and does not let through the lightemitted by the lithography exposure, and is an area where a shield part38 is formed on the glass substrate 37. In the 0% transmittance area,since the resist layer 21 does not harden, the resist layer 21 isremoved in the development process and the substrate 10 is exposed.

On the other hand, as shown in FIG. 4, in the intermediate transmittancearea of 30% transmittance, only a part of the resist layer 21 hardens.Because the 30% transmittance area is sandwiched between the 0%transmittance area and the 100% transmittance area, the 30%transmittance area is influenced by the transmittances of both areas. Asa result, the 30% transmittance area does not have a complete step-like30% transmittance. As shown in FIG. 4, the resist layer 21 becomes ashape including the slope part 25 where a hardened part graduallyincreases from the 0% transmittance area to the 100% transmittance area.By forming the resist pattern 22 into the resist layer 21 including sucha shape, and by performing plating with metal material to fill theresist pattern 22, it is possible to form the metal layer 40 that hasthe bottom surface 42 which is less than the top surface 41 in width andcircumference and has the side surface 43 including the slope part 44 toconnect a width of the top surface 41 and that of the bottom surface 42in lines.

In this way, by setting the transmittance of the glass mask 30 at anintermediate transmittance between 0% and 100%, it is possible to formthe resist pattern 22 extending outward and downward as shown in FIG. 4.A value of the intermediate transmittance between 0% and 100% can be setat various transmittance values according to an intended purpose.

Such an intermediate transmittance between 0% and 100% can be realizedin various ways, for example, by adjusting transmittance of a lightshielding film by changing color or materials, or by making a tintingpart into the glass substrate 37 of the glass mask 30.

Next, by using FIG. 5A through FIG. 10, an explanation is given about amethod of materializing an intermediate transmittance between 0% and100% by a mask pattern 31. In the above-mentioned transmittanceadjustment by changing color or materials of the light shielding film,or by the tinted glass substrate 37, there is a concern that complicatedwork is needed and the adjustment is difficult to practice. Hence, inthe manufacturing method of the substrate for a semiconductor package 50of the embodiment, more detailed explanations are given about amanufacturing method capable of materializing the above-mentionedtransmittance and resist pattern 22 by the shape of a mask pattern 31,without changing materials of the light shielding part 38 and the glasssubstrate 37.

FIG. 5A and FIG. 5B are views showing an example of the shape of a maskpattern 31 of the glass mask 30 used for a lithography exposure processof the manufacturing method of the substrate for a semiconductor device50 of the first embodiment. FIG. 5A is a view showing an example of atop view of the mask pattern 31 of the glass mask 30.

In FIG. 5A, the mask pattern 31 includes a transmission area 37 a, anintermediate transmission area 33 and a light shielding area 32. Thetransmission area 37 a is an area where the glass substrate 37 isexposed and light passes through. When the resist pattern 22 is formedwith a negative type resist layer 21, the mask pattern 31 is mostly madeof the transmission area 37 a that leaves the resist layer 21, andincludes the light shielding area 32 and the intermediate transmissionarea 33 at a position intended to form an opening. The mask pattern 31is configured to include the intermediate area 33 between thetransmission area 37 a and the light shielding area 32.

The light shielding area 32 is an area where the glass substrate 37 isfully covered with the light shielding part 38, and becomes a quadrangleformed with the light shielding part 38. On the other hand, theintermediate transmission area 33 is an area near a border with thetransmission area 37 a, and plural transmission parts 34 are partiallyprovided in an area made of the light shielding part 38, and the lightshielding part 38 and the transmission parts 34 exist in a mixed state.This allows the intermediate area 33 to partially let the light through.Thus, for example, adjustment of the transmittance may be carried out bypartially disposing the transmission parts 34 so that the transmittanceof the intermediate transmission area 33 of the mask pattern 31 becomeshigher than that of the light shielding area 32 among the whole maskpattern 31. From a micro perspective, a part where the light shieldingpart 38 is formed has 0% transmittance, and a part where the glasssubstrate 37 is exposed has 100% transmittance. However, as described inFIG. 4, because the intermediate transmission area 33 is disposedbetween the light shielding area 32 of 0% transmittance and thetransmission area 37 a of 100% transmittance made of the exposed glasssubstrate 37 surrounding the mask pattern 31, the intermediatetransmission area 33 is affected by the transmittances on both sides,and the resist layer 21 under the intermediate transmission area 33becomes a shape including the slope 25. Therefore, without intricatelyadjusting materials themselves such as the glass substrate 37 and thelight shielding part 38, by configuring the glass mask 30 to include thetransmission part 34 made of the same material as the transmission area37 a, and the light shielding part 38 made of the same material as thelight shielding area 32 in a mixed state, it is possible to form theintermediate transmission area 33 of which transmittance is lower thanthat of the transmission area 37 a and is higher than that of theshielding area 38. Furthermore, by using the glass mask 30 includingsuch a mask pattern 31, the resist pattern 22 that includes the slopepart 25 and expands outward and downward can be formed, as shown in FIG.4.

FIG. 5B is a view showing an example of a resist pattern 22 formed by alithography exposure process by using the glass mask 30 including themask pattern 31 shown in FIG. 5A. In FIG. 5B, the whole resist pattern22 forming a hollow part shows the resist pattern 22 formed by the glassmask 30 including the mask pattern 31 of the shape of FIG. 5A. Theresist pattern 22 including a flat top surface 23 remains correspondingto the exposed part of the glass substrate 37 of the mask pattern 31. Alower part of a circumference part corresponding to the intermediatetransmission area 33 of the mask pattern 31 expands inward and downwardin the hollow part, and has the side surface 24 including the slope part25 that makes a circumference of the hollow part gradually smaller. In apart corresponding to the shielding area 32 of the mask pattern 31, thesubstrate 10 is exposed.

In this way, it is possible to form the resist pattern 22 that has theside surface 24 including the slope part 25 by partially disposingplural transmission parts 34 and making the intermediate part 33including the light shielding part 38 and the transmission part 34 in amixed state. Because the intermediate transmission part 33 is disposedbetween the transmission area 37 a of 100% transmittance where the lightshielding part 38 is not formed at all and the light shielding area 32,the whole surface of which is fully covered with the light shieldingpart 38, it is possible to form the side surface 24 including the slopepart 25 by the influence of both of the transmittances with the glassmask 30 of simple configuration. Though the side surface 24 expandsinward and downward of the resist pattern 22 forming the hollow part,and has the slope part 25 of which circumference decreases, seen fromthe resist pattern 22 where resist remains, since the slope part 25expands downward and outward, the explanation does not contradict theabove-discussed description.

FIG. 6A through FIG. 6D are views showing an example of the metal layer40 formed by plating with the resist pattern 22 shown in FIG. 5B. FIG.6A is a view showing an example of the top surface 41 of the metal layer40. FIG. 6B is a view showing an example of a cross section of the sidesurface 43 of the metal layer 40. FIG. 6C is a view showing an exampleof the bottom surface 42 of the metal layer 40. FIG. 6D is a viewshowing an example of a three-dimensional shape reversed vertically.

As shown in FIG. 6A through FIG. 6C, the metal layer 40 formed byplating has the top surface 41 of which perimeter or cross-section areaparallel to the substrate 10 is greater than that of the bottom surface42. The side surface 43 is configured to include the slope part 44 wherea circumference or a cross-section area at a level parallel to thesubstrate 10 decreases at a lower part than at the middle of the sidesurface 43 as the level approaches the substrate 10 or the bottom 42.This makes it possible to prevent the metal layer 40 from being pulledout because sealing resin 80 wraps around an area under the metal layer40, and a force to fight back a downward shift acts on the metal layer40 via the slope part 44 formed around the bottom surface 42 when asemiconductor package is manufactured by using the substrate for asemiconductor package 50 of the embodiment of the present invention.

Furthermore, in FIG. 6D, a three-dimensional oblique perspective view ofthe vertically inverted metal layer 40 is shown. According to aconfiguration of the metal layer 40, even if the metal layer 40 ispulled upward, a downward resistant force acts on the metal layer 40 bywrapping around the slope part 44 near the bottom surface 42 (which isshown at a top side in FIG. 6D) of the side surface 43 with the sealingresin 80.

Next, an explanation is given about various kinds of configurationexamples of the mask pattern 31 of the glass mask 30 in themanufacturing method of the substrate for a semiconductor package 50 ofthe first embodiment using FIG. 7 through FIG. 10.

FIG. 7 is an enlarged view showing a same mask pattern as the maskpattern 31 of the glass mask 30 in the manufacturing method of thesubstrate for a semiconductor package 50 of the first embodimentdescribed until now. In FIG. 7, the mask pattern 31 includes theintermediate transmission area 33 between the transmission area 37 awhere the glass substrate 37 is exposed and the light shielding area 32where the glass substrate 37 is wholly covered with a light shieldingfilm. Also, the intermediate transmission area 33 of the mask pattern 31includes the partial transmission part 34 that is partially formed inthe light shielding part 38. In FIG. 7, if the breadth of theintermediate transmission area 33 is 60 μm, the partial transmissionpart 34 is a square 20 μm on a side, and is formed so that a medianpoint passes through the middle point of the intermediate transmissionarea 33 in a transverse direction. Moreover, the pitch of the adjacentpartial transmission parts 34 in a longitudinal direction is 40 μm.Thus, for example, it is possible to form the partial transmission part34 that has about a one-third width of the intermediate transmissionarea 33. Since a light shielding film part outer to the partialtransmission part 34 is 20 μm, and the partial transmission part 34 is20 μm, transmittance of a whole intermediate transmission area 33 isproperly adjusted.

FIG. 8 is a view showing a mask pattern 31 a of a first modifiedexample. FIG. 8 shows an example where an arrangement of a partialtransmission part 34 a is similar to the mask pattern 31 in FIG. 7, butthe size of the partial transmission part 34 a is different from themask pattern in FIG. 7. In FIG. 8, the partial transmission part 34 a isdisposed on the middle line of the intermediate transmission area 33 athat has a width of 60 μm so that the median points of the partialtransmission parts 34 a agree with each other, and the pitch of theadjacent partial transmission parts 34 a is 40 μm in a longitudinaldirection. Accordingly, the layout relationship of the partialtransmission part 34 a in the mask pattern 31 a is similar to the maskpattern 31 in FIG. 7. However, in FIG. 8, a side of the partialtransmission part 34 a is 10 μm, which is a half of a side of thepartial transmission part 34 in FIG. 7. Thus, a size of the partialtransmission part 34, 34 a can be made an appropriate size according toapplication.

FIG. 9 is a view showing a mask pattern 31 b of a second modifiedexample. FIG. 9 shows an example of the mask pattern 31 b that has apartial transmission part 34 b, 35 b pattern different from the maskpattern 31 in FIG. 7 and the mask pattern 31 a in FIG. 8. The maskpattern 31 b in FIG. 9 differs from the mask pattern 31, 31 a in FIG. 7or FIG. 8 in that there are plural kinds of partial transmission parts34 b, 35 b, of which sizes are different in an area of the lightshielding part 38 of the intermediate transmission area 33 b.

In FIG. 9, regarding the size of the intermediate transmission area 33b, the width is 60 μm that is the same as FIG. 7 and FIG. 8, but thefirst partial transmission parts 34 b of a square 15 μm on a side arecentered at a position of 22.5 μm from a border line with a transmissionarea 37 a at 40 μm pitch in a longitudinal direction.

Furthermore, second partial transmission parts 35 b of a square 5 μm ona side are centered at a position of 55.5 μm from the outercircumference in a transverse direction and at a position in the middleof the adjacent first partial transmission parts 34 b at 40 μm pitch ina longitudinal direction. In other words, the first partial transmissionparts 34 b that have a longer side are disposed on a transmission area37 a side in the intermediate transmission area 33 b, and the secondpartial transmission parts 35 b are disposed on a light shielding area32 side, and the first partial transmission parts 34 b and the secondpartial transmission parts 35 b are disposed alternately in alongitudinal direction.

In this way, it is possible to configure the mask pattern 31 b bypartially disposing plural kinds of partial transmission parts 34 b, 35b in an area of the light shielding part 38 of the intermediatetransmission area 33 b. By disposing the partial transmission parts 34b, 35 b on the transmission area 37 a side and the light shielding area38 side of the intermediate transmission area 33 b, and by fine-tuningthe transmittance, it is possible to adjust the slope 25 of the sidesurface 24 of the resist pattern 22 with a high degree of accuracy.

FIG. 10 is a view showing a mask pattern 31 c of a third modifiedexample. The mask pattern 31 c of the third modified example is similarto the mask pattern 31 b of the second modified example in that thereare plural kinds of partial transmission parts 34 c, 35 c in the area ofthe light shielding part 38. However, a layout pattern of the maskpattern 31 c of the third modified example differs from the mask pattern31 b in the second modified example.

In FIG. 10, an intermediate transmission area 33 c has a width of 60 μmas well as the mask pattern 31, 31 a, 31 b described above. Also, themask pattern 31 c of the third modified example is similar to the maskpattern 31 b in FIG. 9 in that a side length of the first partialtransmission part 34 c with a longer side is 15 μm long, a side lengthof the second partial transmission part 35 c with a shorter side is 5 μmlong, and the first partial transmission part 34 c and the secondpartial transmission part 35 c are alternately arranged at 40 μm pitchin a longitudinal direction.

However, in FIG. 10, the mask pattern 31 c differs from the mask pattern31 b of the second modified example in FIG. 9 in that the second partialtransmission parts 35 c that have shorter sides are disposed at 7.5 μmfrom a border line between the intermediate transmission area 33 c andthe transmission area 37 a on the transmission area 37 a side, and thefirst partial transmission parts 34 c that have longer sides aredisposed at 37.5 μm from the border line between the intermediatetransmission area 33 c and the transmission area 37 a on the lightshielding area 32 side.

In this way, even when plural kinds of partial transmission parts 34 b,35 b, 34 c, 35 c are formed in an area of the light shielding field 38in the intermediate transmission area 33 b, 33 c, the arrangements arechangeable according to application.

As described in FIG. 7 through FIG. 10, side surfaces 24 connectingbetween the top surface 23 and the substrate 10 surface are adjustableso as to have various slope widths and slope angles based on aconfiguration of the mask patterns 31, 31 a to 31 c of the glass mask30, and various shapes of metal layers 40 can be formed according toapplication.

According to the mask patterns 31, 31 a to 31 c in the first embodiment,it is possible to adjust the transmittances of the intermediatetransmission areas 33, 33 a to 33 c by adjusting a ratio between thetransmission part and the light shielding part by changing a maskpattern shape. More specifically, it is possible to adjust thetransmittance of the intermediate transmission area 33, 33 a to 33 c bya size or number of openings, and to perform a flexible transmittanceadjustment despite a simple configuration.

Next, an explanation is given about an example of a manufacturing methodof the semiconductor package 100 by using the substrate for asemiconductor package 50 of the first embodiment with reference to FIG.11A through FIG. 11E. FIG. 11 through FIG. 11E are views showing anexample of the manufacturing method of the semiconductor package 100 ofthe first embodiment.

FIG. 11A is a view showing a semiconductor device mounting process tomount the semiconductor device 60 on the substrate for a semiconductordevice 50. In the semiconductor device mounting process, thesemiconductor device 60 is mounted on the semiconductor device mountingarea 45 of the metal layer 40 formed on the conductive substrate 10. Thesemiconductor device 60 may be mounted on the semiconductor devicemounting area 45 by placing the terminal 61 facing upward, and bybonding a package part to the semiconductor device mounting area 45. Inthis process, by using the substrate for a semiconductor package 50 ofthe embodiment, since the semiconductor device 60 can be mounted on thesemiconductor device mounting area 45 that has a flat surface, thesemiconductor device mounting process can be performed readily andsurely.

FIG. 11B is a view showing a wire bonding process to connect theterminal 61 of the semiconductor device 60 to the electrode 46 of themetal layer 40 by wire bonding. In the wire bonding process, theterminal 61 of the semiconductor device 60 and the electrode 46 areconnected with the bonding wire 70. In this process, by using thesubstrate for a semiconductor package 50, because the wire bonding iscarried out on the electrode 46 that has the flat top surface 41,connection of the bonding wire 70 to the electrode 46 can be performedeasily. In addition, since the electrodes 46 are uniform in size andshape, even if a distance between the terminals 61 of the semiconductordevice 60 is narrow, a short circuit to an adjacent terminal 61 does notoccur, and adapting to miniaturization of the semiconductor device 60 iscertainly possible.

FIG. 11C is a view showing a resin sealing process to seal thesemiconductor device 60 and so on with the sealing resin 80. In theresin sealing process, the semiconductor device 60 on the substrate 10,the bonding wire 70, the semiconductor device mounting area 45 and theelectrode 46 are sealed with the sealing resin 80 from an upper surface,and are thus protected from exterior dust and so on. In the resinsealing process, since a space above the semiconductor 10 is filled withthe sealing resin 80 to cover all the above-mentioned components, spacesbelow lower parts of the semiconductor device mounting area 45 andelectrode 46 on the substrate 10 are all filled with the sealing resin80 and fixed.

FIG. 11D is a view showing a substrate removal process to remove thesubstrate 10. In the substrate removal process, there are a substrateremoval method that removes the substrate 10 by peeling the substrate 10from below and a substrate removal method that removes the substrate 10by dissolving the substrate 10 in solvent.

If the substrate 10 is removed by peeling, to peel the substrate 10 offfrom below, a force pulling down acts on the metal layer 40 includingthe semiconductor device mounting area 45 and the electrode 46electrodeposited on the substrate 10. In this case, if the metal layer40 including the semiconductor device mounting area 45 and/or theelectrode 46 has the same size for the top surface 41 and the bottomsurface 42, and has the side surface 43 parallel to the verticaldirection, there is a risk of the metal layer 40 falling out of thesealing resin 80 when the substrate 10 is pulled downward and peeledoff. However, in the substrate for a semiconductor device 50, becausethe side surface 43 of the metal layer 40 has a side shape including theslope part 44 of which decreases in circumference as the circumferenceapproaches the bottom surface 42, the sealing resin 80 acts on the metallayer 40 resisting the downward force, which makes it possible to removeonly the substrate 10 from the metal layer 40 and the sealing resin 80.

On the other hand, when the substrate 10 is removed by dissolving, thesubstrate 10 is immersed in solvent that does not affect the sealingresin 80, and the substrate 10 is dissolved and removed. In this casealso, in the substrate for a semiconductor package 50, because a borderline between the metal layer 40 and the sealing resin 80 is long,intrusion of water can be prevented. This improves humidity resistance,which leads to improved reliability of the semiconductor package 100.

In addition, because the sealing resin 80 acts on the metal layer 40 soas to resist the downward force, it is possible to ensure bondingstrength after soldering the semiconductor package 100 onto a substratefor electronic components (which are not shown in FIG. 11D).

FIG. 11E is a view showing a dividing process that divides thesemiconductor package 100 including plural of the semiconductor devices60 to form a semiconductor package 100 for each semiconductor device 60.In the dividing process, by cutting the sealing resin 80 in a verticaldirection, semiconductor packages 100 including an exposed semiconductordevice mounting area 45 and an exposed outer terminal 47 that is abottom surface of the electrode 46 on its bottom surface are completed.

In this way, according to the semiconductor package 100 of theembodiment, because the semiconductor package 100 is manufactured byusing the substrate for a semiconductor package 50 including the metallayer 40 of which width or circumference at a level decreases as thelevel approaches the substrate 10, it is possible to surely peel off thesubstrate 10 and to efficiently manufacture the semiconductor package100. In addition, because the metal layer 40 has a flat top surface 41,mounting the semiconductor device 60 or wire bonding can be readily andsurely performed. Furthermore, since the metal layer 40 has a low heightand a uniform shape and size, it is possible to respond tominiaturization of the semiconductor device 60 sufficiently.

Second Embodiment

FIG. 12A and FIG. 12B are views showing an example of a partialconfiguration of a substrate for a semiconductor package 50 a of asecond embodiment. FIG. 12A is an enlarged view showing an example of apart of a metal layer 40 a. FIG. 12B is a view showing an example of aplating process of a manufacturing method of a substrate for asemiconductor device 50 a of the second embodiment.

In FIG. 12A, a side surface 43 a of the metal layer 40 a has a shapewhere a top surface 41 a, of which width is larger than that of a bottomsurface 42 a, and a side surface 43 a includes a slope part 44 a whichdecreases in circumference as the circumference approaches the bottomsurface 42 a, at a part around the bottom surface 42 a. Therefore, themetal layer 40 a has a shape that makes it difficult to be pulled outdownward as well as the metal layer 40 of the substrate for asemiconductor package 50 in the first embodiment. More specifically, bysuch a slope, the substrate for a semiconductor device 50 a has a shapewhere sealing resin supports and fixes the metal layer 40 a including anelectrode 46 and/or a semiconductor device mounting area 45 from belowobliquely upward, and a binding force between the sealing resin and theelectrode 46 and/or the semiconductor device mounting area 45 can beimproved.

However, in FIG. 12A, referring to a top view and a bottom view of themetal layer 40 a, the circumference of the top surface 41 a has asaw-tooth appearance and has a zigzag shape 48. On the other hand, thebottom surface 42 a has a square shape with round corners as well as thebottom surface 42 of the substrate for a semiconductor device 50 a ofthe first embodiment. In this manner, the metal layer 40 a may have thetop surface 41 a, of which circumference is formed into a zigzag shape48 like saw teeth. By forming the circumference into the zigzag shape48, when the metal layer 40 a is sealed with resin, it is possible toincrease a contact area with the sealing resin 80 and bonding strength.Moreover, when the substrate for a semiconductor device 50 a isconfigured as a semiconductor package 100, since the top surface 41 a ofthe metal layer 40 a is hidden by resin sealing, there is no request foran appearance configuration. There is flexibility capable of takingvarious shapes as long as the shape is superior in function. On theother hand, when configured as the semiconductor package 100, since thebottom surface 42 a becomes an outer terminal 47 by being exposed from abottom surface of the semiconductor package 100, it is desirable for thebottom surface 42 a to have a rectilinear circumference shape, not azigzag shape 48. The bottom surface 42 a of the metal layer 40 a on thesubstrate for a semiconductor package 50 a has a shape that meets such arequest.

In this way, the metal layer 40 a of the substrate for a semiconductorpackage 50 a of the second embodiment has a shape that makes itdifficult to be pulled out downward. More specifically, the top surface41 a with a lot of flexibility in shape is configured to have the zigzagshape 48 that enhances adherence force. The bottom surface 42 a thatworks as the outer terminal 47 is shaped as an approximate square with arectilinear circumference. This can improve the prevention effect of themetal layer's being pulled out even more.

FIG. 12B shows an example of a plating process of the manufacturingmethod of the substrate for a semiconductor package 50 a of the secondembodiment. The plating, process is carried out after forming a resistpattern 22 a on a substrate 10 as well as the first embodiment. Thus, byforming the resist pattern 22 a so that a top surface circumference hasthe zigzag shape 48 of a saw-tooth appearance, the shape of the metallayer 40 a shown in FIG. 12A can be realized.

FIG. 13A and FIG. 13B are views showing an example of the mask pattern31 d shape of the glass mask 30 and a resist pattern 22 a used for alithography exposure process of the manufacturing method of thesubstrate for a semiconductor device 50 a of the second embodiment.

FIG. 13A is a view showing an example of a mask pattern 31 d of a glassmask 30 used for a lithography exposure process of the manufacturingmethod of the substrate for a semiconductor device 50 a of the secondembodiment. In FIG. 13A, the mask pattern 31 d includes a transmissionarea 37 a, an intermediate transmission area 33 d and a light shieldingarea 32 d. The mask pattern 31 d, for example, is configured by forminga light shielding part 38 with a predetermined shape of a lightshielding film on a glass substrate 37. The transmission area 37 a is anarea where the glass substrate 37 is exposed. The light shielding area32 d is an approximately square area where the light shielding part 38is fully formed as well as the mask pattern 31 in the first embodiment.The mask pattern 31 d has the intermediate area 33 d between thetransmission area 37 a and the light shielding area 32 d. These mattersare similar to the mask pattern 31 in the first embodiment.

On the other hand, the intermediate area 33 d has a shape that includesa saw-like border line of zigzag shape 36 as a border between an area ofa transmission part 39 and an area of light shielding part 38. In thisway, by making the border line that divides the area of the transmissionpart 39 and the area of the light shielding part 38 in the intermediatearea 33 d have the zigzag shape 36, the resist pattern 22 a that has atop surface of the zigzag shape 36 can be formed. When the mask pattern31 a that has such a pattern is used, it may be thought that the zigzagshape 36 is formed in the same shape from the top to a lower part.However, because the intermediate transmission area 33 d is providedbetween the light shielding area 32 d of 0% transmittance and thetransmission area 37 a of 100% transmittance, as well as the explanationin the first embodiment, the intermediate transmission area 33 d isaffected by both transmittances. As a result, the transmittance of theintermediate transmission area 33 d becomes between 0% and 100%, higherthan the light shielding area 32 d and lower than the transmission area37 a. Therefore, as the level of resist 20 is lowered, influence fromthe mask pattern 31 d becomes weak, and the transmittance comes close tothe transmittance where an intermediate transmittance area is providedas the intermediate transmission area 33 d. Then, the zigzag shape 36becomes smaller as the level approaches the substrate 10. In otherwords, in this case, the intermediate transmission area 33 d includes alight shielding part 38 that has a zigzag circumference and a zigzagtransmission part to fit the zigzag shape 36 of the light shielding part38 in a mixed state. With this, it is possible to make the transmittanceof the intermediate area 33 d higher than the light shielding areacompletely covered with a mask, and to adjust the transmittance with asimple mask shape.

FIG. 13B is a view showing an example of the resist pattern 22 a that isexposed with a glass mask 30 of the mask pattern 31 d in a lithographyexposure process and is formed in a development process. In FIG. 13B, atop surface 23 a of the resist pattern 22 a includes a zigzag shape 36in the almost same shape as the mask pattern 31 d, formed bytransferring. The zigzag shape 36 of a side surface 24 a decreases asthe zigzag shape 36 approaches the substrate 10 of a bottom surface.Around the substrate 10, the side surface 24 a includes a slope part 25a that extends inward and downward in a hollow and whose circumferencebecomes small. Due to the slope part 25 a, a slope part 44 a (See FIG.12A) can be formed into the metal layer 40 a, which becomes a shape thatmakes it possible to apply a force upward after being sealed withsealing resin 80.

FIG. 14A through FIG. 14D are views showing an example of a shape of themetal layer 40 a formed by a plating process with the resist pattern 22a described in FIG. 13A and FIG. 13B. FIG. 14A is a top view of themetal layer 40 a. FIG. 14B is a side view of the metal layer 40 a. FIG.14C is a bottom view of the metal layer 40 a. FIG. 14D is athree-dimensional oblique view of an inverted metal layer 40 a.

As shown in FIG. 14A, a circumference of a top surface 41 a of the metallayer 40 a has a saw-like zigzag shape 48, which can increase thecontact area of the side surface 43 a with sealing resin 80 and canimprove bonding force. In addition, as shown in FIG. 14C, a bottomsurface 42 a of the metal layer 40 a has a smaller area than the topsurface 41 a, and is an approximate square that is used as the outerterminal 47 in general.

Moreover, as shown in FIG. 14B, in a cross-sectional shape of the metallayer 40 a, a slope shape 44 a where a cross-sectional area surfaceparallel to the substrate 10 decreases as the surface parallel to thesubstrate 10 approaches the bottom surface 42 a is formed around thebottom surface 42 a. Also, the zigzag shape 48 of the top surface 41 adecreases at a level as the level approaches the bottom surface 42 a.The slope part 44 a has a shape capable of applying an upward force whenreceiving a pull downward force after being sealed with the sealingresin 80. Therefore, the metal layer 40 a is configured to be able toprevent the metal layer 40 a from being pulled down in a substrateremoval process of the manufacturing method of the semiconductor package100. Furthermore, the top surface 41 a has a flat surface, which isappropriate for semiconductor device 60 mounting and wire bonding. Thismakes it possible to improve adhesion strength for semiconductor devicemounting and to facilitate and bind strongly connections between aterminal of the semiconductor device and an electrode by wire bonding.In addition, because there is no flared part in a transverse direction,and a height is less than or equal to the resist pattern 22 a, the metallayer 40 a has a shape sufficiently capable of responding tominiaturization and meeting demands for high accuracy of a metal layerof a substrate for a semiconductor device 50 a.

FIG. 14D is a three-dimensional oblique perspective view of a verticallyinverted metal layer 40 a. In FIG. 14D, the bottom surface 42 a to bethe outer terminal 47 has a flat surface. Also, the metal layer 40 a hasa structure where sealing resin wraps around the slope part 44 a formedinto the side surface 43 a near the bottom surface 42 a, which is ashape capable of preventing movement of the metal layer 40 a byproviding a downward force even if an upward force acts.

According to the semiconductor package 100 of the second embodiment, itis possible to solidly maintain a binding force between the sealingresin 80 and the metal layer 40 a by the zigzag shape 48, and to preventthe metal layer 40 a from falling out of the sealing resin 80 becausethe metal layer 40 a tapers downward. In addition, it is possible toprevent water intrusion from a back side of the semiconductor package100 through borders between the metal layer 40 a or an electrode and thesealing resin layer 80, and to realize superior water resistance. Also,it is possible to carry out wire bonding and semiconductor devicemounting easily on a flat surface and to improve adhesion force of thewire bonding and the semiconductor device mounting.

Since a manufacturing method of the substrate for a semiconductorpackage 50 a of the second embodiment is similar to the manufacturingmethod of the substrate for a semiconductor package 50 described in thefirst embodiment except for the mask pattern 31 d of the glass mask 30in the lithography exposure process, the explanation is omitted.

According to the manufacturing method of the substrate for asemiconductor package 50 a of the second embodiment, it is possible tomake the substrate for a semiconductor package 50 a have a configurationthat improves adhesion force by increasing a contact area between themetal layer 40 a and the sealing resin 80 by forming the zigzag shape 48into an upper part, and to form the metal layer 40 a that has a shapeappropriate to use its bottom surface as an outer terminal because thezigzag shape 48 becomes smaller on the substrate 10 side.

Moreover, with regard to a semiconductor package 100 manufactured byusing the substrate for a semiconductor device 50 a of the secondembodiment and a manufacturing method of the semiconductor package 100,since an explanation is similar to that in the first embodiment, theexplanation is omitted.

In the above-discussed embodiments, the first embodiment and the secondembodiment can be combined, and descriptions in the first embodiment canbe applied to the second embodiment.

Furthermore, the lithography exposure process of the first embodimentand the second embodiment is explained by citing an example of alithography exposure process that forms a resist pattern 22 with anegative type resist 20, and configurations of the mask patterns 31, 31a to 31 d relate to negative type mask patterns. However, amanufacturing method of a substrate for a semiconductor package, amanufacturing method of a semiconductor package, a substrate for asemiconductor package and a semiconductor package of the presentinvention are applicable to a positive type mask pattern. If a glassmask 30 corresponding to a positive type resist 20 is used, by invertinga layout relationship between the transmission area 37 a and the lightshielding area in the mask patterns 31, 31 a to 31 d described in theembodiments, and by inverting a layout relationship between thetransmission part 34, 34 a to 34 c, 39 and the light shielding part 38in the intermediate transmission areas 33, 33 a to 33 d, the descriptionin the first embodiment and the second embodiment can be directlyapplied.

According to the above-discussed embodiments of the present invention,it is possible to form a metal layer on a substrate for a semiconductorpackage with a shape that improves its adhesion power with a sealingresin.

More specifically, according to the manufacturing method of thesubstrate for a semiconductor package of the above-discussedembodiments, it is possible to form a metal layer that has a side shapeincluding a slope shape where a circumference at a level decreases asthe level gets close to a substrate side; if the substrate is peeled offafter resin sealing, a state where the sealing resin supports the slopepart of the metal layer from below is formed, and enough tolerability ismaintained in the following semiconductor manufacturing processes.

Furthermore, it is possible to make a top surface of the metal layerflat, to make a width in a transverse direction uniform, and tosufficiently adapt to miniaturization of a semiconductor package and thedistance between terminals of a semiconductor package.

Moreover, it is possible to utilize a metal layer that has a shapecapable of ensuring tolerability as an electrode or a semiconductordevice mounting area of a substrate for a semiconductor mounting: it ispossible to make use of a metal layer shaped to have high tolerability.

According to the manufacturing method of the semiconductor package ofthe above-discussed embodiments of the present invention, in a processof removing a substrate from a semiconductor package, it is possible todecrease a concern that a metal layer may be pulled out of sealing resinfrom which the substrate is being removed, and to manufacture asemiconductor package with a high throughput.

Also, adequate adhesion strength can be ensured after soldering asemiconductor device on a substrate for electronic components.Furthermore, it is possible to prevent water intrusion from a back sideof a semiconductor package through border parts between a metal layer oran electrode layer and a sealing resin layer, which can realize superiorhumidity resistance.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority orinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

1. A manufacturing method of a substrate for a semiconductor packagecomprising: a resist layer forming step to form a resist layer on asurface of a conductive substrate; a lithographic exposure step toexpose the resist layer using a glass mask with a mask pattern includinga transmission area, a light shielding area, and an intermediatetransmission area disposed between the transmission area and the lightshielding area, wherein transmittance of the intermediate transmissionarea is lower than that of the transmission area and is higher than thatof the light shielding area; a development step to develop the resistlayer and to form a resist pattern including a hollow with a side shapeincluding a slope part decreasing in hollow circumference as the hollowcircumference approaches the substrate; a plating step to plate on anexposed area of the substrate by using the resist pattern and to form ametal layer with a side shape including a slope part decreasing incircumference as the circumference approaches the substrate; and aresist removal step to remove the resist pattern.
 2. The manufacturingmethod of the substrate for a semiconductor package as claimed in claim1, wherein the intermediate transmission area of the mask patternincludes a mixture of a transmission part with the same transmittance asthat of the transmission area and a light shielding part with the sametransmittance as that of the light shielding area.
 3. The manufacturingmethod of the substrate for a semiconductor package as claimed in claim2, wherein the intermediate transmission area partially includes thetransmission part in the light shielding part.
 4. The manufacturingmethod of the substrate for a semiconductor package as claimed in claim2, wherein the intermediate transmission area includes a zigzag borderline dividing the transmission part and the light shielding part.
 5. Themanufacturing method of the substrate for a semiconductor package asclaimed in claim 4, wherein the hollow of the resist pattern has a sideshape including a zigzag shape circumference similar to the zigzagborder line in a top surface of the resist pattern, and a smaller zigzagshape circumference than that of the top surface as the circumferenceapproaches the substrate.
 6. The manufacturing method of the substratefor a semiconductor package as claimed in claim 1, wherein the metallayer is formed with a thickness less than that of the resist pattern inthe plating step.
 7. The manufacturing method of the substrate for asemiconductor package as claimed in claim 1, wherein the metal layer isan electrode for wire bonding or an area for supporting a semiconductordevice.
 8. The manufacturing method of the substrate for a semiconductorpackage as claimed in claim 1, further comprising: a resist patternstabilization step to expose the resist pattern between the developmentstep and the plating step.
 9. A manufacturing method of a semiconductorpackage comprising: a resist layer forming step to form a resist layeron a surface of a conductive substrate; lithographic exposure step toexpose the resist layer using a glass mask with a mask pattern includinga transmission area, a light shielding area, and an intermediatetransmission area disposed between the transmission area and the lightshielding area, wherein transmittance of the intermediate transmissionarea is lower than that of the transmission area and is higher than thatof the light shielding area; a development step to develop the resistlayer and to form a resist pattern including a hollow with a side shapeincluding a slope part decreasing in hollow circumference as the hollowcircumference approaches the substrate; a plating step to plate on anexposed area of the substrate by using the resist pattern and to formmetal layers with a side shape including a slope part decreasing incircumference as the circumference approaches the substrate; a resistremoval step to remove the resist pattern; a semiconductor devicemounting step to mount a semiconductor device on one of the metal layersof the substrate; a wire bonding step to connect a terminal of thesemiconductor device to another metal layer of the metal layers as anelectrode; a sealing step to seal the semiconductor device mounted onone of the metal layers of the substrate with resin; and a substrateremoval step to remove the substrate from the semiconductor device.